Snap switch



Aug. 23, 1938.. J HATHORN 2,127,686 w SNAP SWITCH Filed Jan. 7, 1937 2 Sheets-Sheet l ATTORNEY.

c. J. HATHORN SNAP SWITCH Filed Jan. 7, 1957 Aug. 23, 1938- 2 Sheets-Sheet 2 INVENTOR.

C/ re CeJ HWZ/JOFOI A TTORNE Y.

Patented Aug. 23, 1938 UNITED STATES PATENT OFFICE SNAP SWITCH Application January 7, 1937, Serial No. 119,375

'7 Claims.

My invention relates to a control for'an electric circuit and relates particularly to a snap switch for completing or interrupting the electrical circuit at the option of the operator.

In my prior patent application Serial No. 701,802, filed December 11, 1933, I have disclosed a pivoted bridging member which makes a good contact with the stationary contact terminals even though there is a slight variation of the throw arm or the fixed terminals from their predetermined correct position.

In certain switches where the circuit is completed by the bridging of two fixed or stationary terminals by a non-pivotal bridging member, the incorrectpositioning of one or both of the fixed terminals may result in one portion of the bridging member being spaced a small distance from one of the terminals. This spacing of the bridging element from the live terminal results. in an 20 arc being established between the separated live elementswith its destructive result of eroding or pitting of the electrical contact surfaces which establishes a high resistance, and also reduces the efiective life of the switch, since the terminals and/or the bridging member will be burned away. v

Furthenin switches where thethrow arm is pivotally mounted and where the bridging member is pivotally rotated into bridging position, the force or torque imparted to the bridging 'member bythe throw arm is normal to an imaginary radius drawn between the point of application of the force and the pivot point. However, if the pintle or pivot for the bridging inemher is comparatively near tothe turning force (that is the throw arm) "then a freezing or sticking of the electrical bridging member makes the device inoperative. v I 1 Therefore, an object of my invention is to which will be eifective in operation even though some elements may be improperly aligned during the course of manufacture.

It is a further object of my invention to minimize the sparking or arcing between the terminals and their cooperative-bridging member.

It is another object of my invention to provide a. frictional or sliding or wiping contact between the stationary electricalfterminals and the mov- 50 able electrical bridging member whereby the terminalswill alwaysbe kept clean or will of themselves brush aside any dust or dirt that may collect thereon.

Another object of my invention is to obtain. i5 a'verylowccntact resistance between the bridgconstruct a snap switch which will not stick and ing member and the terminals. As a corollary, an object of my invention is to minimize the heating of the elements of the switch by reducing the contact resistance. v

A still further object of my invention is to 5 simplify the construction of the device so that it may be manufactured in quantity lots at a low cost.

A still further object of my invention is to construct an interfitting elongated rece'ssor open- 10 ing on a bridging member which is cooperative with a pin whereby the pressure of each side of the bridging member may be equalized or evenly distributed when the-bridging member is in closed circuit position.

Other objects of my invention are to provide an improved device of the character described,

which is simple and economical in construction, and which possesses a maximum amount of serviceability and of strength. c 20 With the above and related objects in View, my invention consists in the details of construc-, tion and the combination of parts that will hereinafter be fully described when the description is read in conjunction with the accompanying 2: drawings in which:

Fig. 1 is a'plan view or a snap switch embodying my invention.

Fig. 2 is a sectional viewtaken on the line 22 0f 1. V I

Fig. 3 is an exploded view of the elements comprising the snap switch.

Fig. 4 is a diagrammatic view of a bridging member which can only be oscillated and wherein a terminal shown in dotted lines is. incorrectly located. The diagram shows a main contact surface of the bridging member being spaced from the incorrectly aligned stationary contact terminal.

Fig.5 is a diagrammatic view of a bridging member which can be oscillated and which also can be moved in a linear direction toproperly engage fixed contactsone of said contacts being improperly aligned. I Fig. 6 is a fragmentary sectional view showing my improved switch connected to avolume control or rheostat.

' Fig. '7 is aside view of a modification of my invention. 1

Fig.8 is a front view of Fig. 7.

Fig. 9 is an exploded View of another modification of the bridging member and the insulating bushing.

Fig. 10 isan exploded view of still another modification of the bridging member and throw arm.

Fig. 11 is a fragmentary sectional view of a modification of the base having a molded pintle therein about which the electrical bridging member oscillates.

Referring now in greater detail to the drawings, in Fig. 1 is shown a type of snap switch wherein the overall diameter of the switch is aproximately 13 g inches and the overall thickness of the base is approximately A inch. The switch mechanism hereinafter further described is mounted within a chamber of an insulated base, generally designated A, which is preferably comprised of a molded phenolic condensation product. A body portion I0 of the base is substantially flat and from its periphery extends a flange H which is substantially circular on its outer bounding surface. The flange has a plurality of recesses or notches i4, i5, and I6 on its inner curved portion, and the recesses or notches communicate directly with the central chamber of the base. The function of the notches I4, 15, and 16 will be hereinafter described in conjunction with the various elements which they complement.

A plurality of small openings l8, I9, 20, 2|, 22 and 23 are formed in the base. The surface defining the opening 22, centrally located in the base, serves as a bearing for a freely longitudinally movable insulating pin or pintle; generally designated as B. The insulating pintle B comprises a cylindrical shaft 24 and an enlarged head 2%. An electrical bridging member or blade, generally designated as C, oscillates about the shaft of the equalizing pintle B as its pivot, and it also supports an insulating washer, generally designated as D. I

The enlarged head 26 is pressed downwardly by a throw arm, generally designated as E,'which presses on the upper surface of the head 26, thus preventing the bridging member from falling out of position. The washerD serves as an electrical insulator between the steel throw arm E. and the spring H, which is on one side, and the metallic bridging member, which is on the other side.

Openings 2! and 23 are spaced from one :another on the circumference of an imaginary circle which has its center substantially in the central axis of-the opening 22, and the openings 2! and 23 receive the shank of each of the electrical conducting rivets 28 and 30.

Each of the electrical conducting rivets 28 and 30 are similarly constructed so that a description of one rivet or contact will suffice as the description of all the rivets or terminals. Rivet 28 has an enlarged intermediate portion 3| which is flat on one side and abuts-against the base-and its upper surface (the auxiliary or arcing stationary contact) is formed in the shape of a, truncated cone, and from the smaller diameter of the truncated cone extends the bridging member contact portion 32 (the main stationary contact). The purpose and functionof this structure is more fully set forth in my prior ,patent application Serial No. 701.802, filed December 11, 1933, which I have already mentioned.

The outside of the shank of the rivet 28 is expanded to hold a terminal 34 to which exterior terminal 3d a flexible electrical lead Wire may be soldered or otherwise suitably attached thereto.

The end of the rivet 28 adjacent the outside terminal 3A is expanded to retain the rivet and terminal 34 firmly together, and also establishes a good electrical contact between the rivet and the terminal. The openings [9 and 20 serve as openings for rivets which retain the snap switch to avolume control or rheostat which forms a combined volume control and snap switch unit, both devices usually being operated by a single control shaft. The switch is usually operated at a predetermined portion of movement of the control shaft.

A trigger and bridging member pivot or pintle, generally designated as F, is located within the recess M and is of the type described in my prior Patent No. 2,057,829, granted October 20, 1936. Upon the pintle F is pivotally mounted the metallic throw arm E as well as a trigger, generally designated as G, the latter being the actuated element of the snap switch whereby the switch is operated to open or to closed circuit positions. The throw arm E is located between the trigger G and the base, and the metallic arm E has its free end 34 slightly offset from its pivotally held end An opening 38 on the longitudinal axis and adjacent one end of the throw arm is substantially circular and is of a diameter to readily fit over the largest diameter of the pintle, in order to expedite the assembly of the throw arm of the pintle during the steps in assembling the elements of my snap switch. The circular opening 38 merges with an elongated slot 39 which is of a width whereby it may oscillate or pivot about the bearing F. A small central opening 40 in the longitudinal axis of the throw arm receives a bushing 42, the bushing'in turn receiving the tip 44 of one leg of the torsional spring, enerally designated as H. p An elongated opening 46 on the end 34 of the throw arm receives an insulating bushing 48, and the bushing 48 is constructed so that its diameter is less than the width of the opening 46. However, a head 50' of the insulating bushing is of greater width than the width of the opening so that the bushing cannot pass through the throw arm opening 46.

The bore 52 of the bushing receives the end or tongue 54 of the lever arm-56 of the bridging member C. The bridging member or blade C has a substantially flat central portion 58 and offset contacting arms 60 and GI.

The movable arm 6| has an auxiliary or aroing surfaceGlA, which surface first engages the auxiliary stationary contact 3| where the arc is made, and the vertically extending front or main contact surface GIB engages the main stationary contact 32. When the contacts are separated, the auxiliary stationary contact 3| and the arcing surface GIA are the last surfaces to separate thus taking the arc, hence preserving the main contact surfaces. An arrangement similar to the above is made for the stationary terminal 30 and the movable arm 60.

From the central portion 58 of the electrical I blade C extends the lever arm 54 which is at right angles to the contact arms 60 and 6|. An elongated rectangular-like slot or opening .62 cooperatively receives the insulating pintle B, and the length of the slot 62 is longer than the diameter of the pintle shank 24. This is for the purpose of having the blade move in a linear direction. The elongated slot 62 has its longitudinal axis disposed at an acute angle with respect to the line joining the main contact surfaces 60B and BIB of the blade C. This angular construction of the slot 62 prevents any sticking of the pintle B and the surfaces defining the slot 62.

It is to be observed at this point-that the stationary terminals 28 and 30 limitthe movement of the bridging member C in. a clockwise direction which also is the position of the bridging member when the circuit is closed, and the throw arm E and wall 10 limit movement of the bridging member C when it is moved in a' counterclockwise direction. The bridging element C may not only oscillate about pintle B, but it may move one of the terminals in the base, then one of the terminals would not receive the full movable contact pressure since the other terminal would prevent movement of the throw arm in a rotary direction, and when current flows, an arc would exist in the space, hence pitting the contacts. However, with an equalizing arrangement such as the elongated angularly disposed slot 62, illustrated diagrammatically in Fig. 5, then the bridging member C is not constrained by its pintle or the lever arm but is free to move in a linear direction because of the respective elongated slots 62 and 46.

By the above structure, it is readily seen that errors committed in assembling the unit -or in constructing the elements of the switch .will not result in excessive pitting of the terminals or the bridging member with its detrimental eifect of creating high resistance and shortening the life of the switch. l 1

A fiat torsional expansion spring H having a central portion coiled has one tip 44 enter the bushing 42, and the other tip 64 enter an openingin the notch formed at the free end of the trigger G. The torsional "spring not only imparts rapid movement orsnap action to the throw arm when the trigger G is moved to a point whereby the dead center position of the spring is reached, but thetorsional spring H tends to press the throw arm in. a direction towards the base. This dual effect of; the spring keeps the throw arm pressed upon the head of the pintle B. The trigger G has upturned arms 66 and 61 which are engaged by an eccentrically positioned pin H which may be on an insulating plate 12 of a volume control, generally designated as V, as shown in my prior issued Patent No. 2,057,839.

In order to actuate the snap switch, either the arm 66 or the arm 61 of the trigger may be engaged by the eccentrically mounted pin H which projects normally to thev plane of the volume control insulating disc "depending on the position of the eccentrically' mounted pin and the position of the ears 66 or 61.

A washer 69 is placed adjacent the metallic trigger G, and the upper end of the trigger pin F is peened over to hold the triggerarld throw arm in position.

It is to be observed that the coiled portion of the spring H which tends to exert an expansive force freely moves in the recess l5. The tip 34 of the throw arm moves in the recess l6 and a wall 10, partially defining the recess l6, engaged by the side of the throw arm when the switch is in open circuit position limits the movement of the throw arm when the throw arm 'E, Fig. 1, ismoved in a counterclockwise direction.

In Figs. 7 and'8, I showa modified construction of my improved snap switch wherein the elements designated by the same reference character or numeral as those shown in Fig. 3 are of similar construction. However, the toggle trigger J is substantially fiat and has an opening in'one end 80, which opening receives a portion of the torsional spring H, and two spaced arms 82, 83 extend outside of the flange 12 but in the same plane as the fiat body portion 80. t

Fig. 9 shows another -modification of my invention showing an insulating bushing which serves as a pivotal connection between the metallic throw arm E and the oscillatory blade CI. The electrical conducting bridging blade CI moves around a central pivot or pintle B and has its turning force appliedto a lever arm which extends substantially in the same plane as the major portion of the bridging member. In other words, the lever arm 90 extends substantially parallel to the throw arm E. An insulating pivot K has an enlarged portion 92, and the transverse end has a slot 94 which receives the lever arm 90 of blade Cl. A narrow circular portion 96 on the pin K interfits with the elongated slot 46 in the throw arm whereby the pin K may slide bodily the entire length of the throw arm opening 46.

, The diameter of the'enlarged portion 92 is greater than the width of the slot 4'6 so that the pin does not pass through the slot. The pressure on the throw arm by the torsional spring prevents the various elements from separating from their operative relationship. The main contact surfaces 600 and BIC on bridging member Ci are arranged similarly to the main contact surfaces MB and 6 B on blade C. The slot 62C is arranged similarcan be forced on arms 96 and 98 so that the metallic arm El will be insulated from the bridging member C2.

In Fig. 11 I show a modification of the molded base wherein a pintle or stud W6 is integrally formed with the base, and the pintle I06 interfits with an opening in the bridging member C.

Although my invention has been described in considerable detail, such description is intended as illustrative rather than limiting, since the invention may be variously embodied, and the scope of the invention is to be determined as claimed.

I claim as my invention:

1. A snap switch comprising an insulating base, a pivot, a forked trigger pivotally. mounted on said pivot, a metallic throw armv pivotally mounted at one end and having an elongated opening at the other end, means between said trigger and said throw arm for pressing said throw arm in a direction towards the base and for imparting rapid movement to saidthrow'arm when said trigger is moved to a predetermined position, a plurality of fixed electrical terminals mounted on said base, an electrical bridging member for engaging said terminals whereby the circuit will be closed, a pintle on said base located between said terminals, said bridging member having an enlarged opening therein for receiving said pintle, a lever arm connected to said bridging member, and an insulating bushing movably mounted in the opening of said throw arm and receiving a portion of said lever arm whereby movement of said throw arm will oscillate said bridging memher, said enlarged openings on said throw arm and said bridging member enabling the bridging member to exert equal pressure on each terminal when the switch is in closed circuit position.

2. A snap switch comprising an insulated base, a plurality of stationary electrical terminals mounted in said base, an electrical bridging member having a lever arm, said bridging member adapted to engag and to be disengaged from said stationary terminals, an insulating pintle having an enlarged head, said pintle loosely mounted in said base and about which said bridging member oscillates, said bridging member having an enlarged opening which cooperatively receives the insulating pintle, the enlarged head of said pintle pressing the bridging member in a direction towards the base, a throw arm and a trigger each of which is pivotally mounted, a spring connected between said trigger and said throw arm whereby rapid movement will be imparted from said trigger to said throw arm, said spring also being adapted to press the throw arm in a direction towards the head of said pintle, and said throw arm having an elongated opening to loosely receive the lever arm of said bridging member whereby said bridging member exerts equal pressure on each terminal when the switch is in closed circuit position.

3. A snap switch comprising an insulating base, a forked trigger pivotally mounted, a metallic throw arm pivotally mounted, a torsional spring between said trigger and said throw arm for pressing said throw arm in a direction towards the base and also for imparting rapid movement to said throw arm when the trigger is moved to a predetermined point; a plurality of fixed electrical contact terminals, a pintle on said base located betwen said terminals, an electrical bridging member for engaging said terminals to close the circuit, an insulating bushing, said bushing interfitting with an elongated opening in the free end of said throw arm, said bridging member having an enlarged opening for receiving said pintle, a lever arm connected to said bridging" member, and a portion of said lever arm interfitting with said bushing in said throw arm whereby movement of said throw arm will oscillate said bridging member about said pintle so that the pressure on the terminals will be equalized when the switch is in closed circuit position.

4. A snap switch comprising an insulating base, a forked trigger pivotally mounted, a metallic throw arm pivotally mounted at one end and having an elongated opening at the other end, means between said trigger and said throw arm for pressing said throw arm in a direction towards the base and for imparting rapid movement to said throw arm when said trigger is moved to a predetermined position, a plurality of fixed electrical terminals mounted on said base, an electrical bridging member for engaging said terminals whereby the circuit will be closed, a pintle on said base located between said terminals, said bridging member having an enlarged opening therein for receiving said pintle, a lever arm connected to said bridging member, and an insulating bushing movably mounted in the opening of said throw arm and receiving a portion of said lever arm whereby movement of said throw arm will oscillate said bridging member, said enlarged openings on said throw arm and said bridging member enabling each contact member of the bridging member to exert equal pressure on each terminal when the switch is in closed circuit position.

5. A snap switch comprising an insulated base, a plurality of stationary electrical terminals mounted in said base, an electricalbridging member having a lever arm, said bridging member adapted to engage and to be disengaged from said stationary terminals, an insulating pintle having an enlarged head and looselymounted in said base and about which pintle said bridging member oscillates, said bridging member having an enlarged opening which cooperatively receives the insulating pintle, the enlarged head of said pintle pressing the bridging member in a direction towards the base, a throw arm and a trigger each of which is pivotally mounted, a spring connected between said trigger and said throw armwhereby rapid movement will be imparted from said trigger to said throw arm and also to press the throw armin a direction towards the head of said pintle, an insulating bushing interfitting with an elongated opening of said throw arm, a portion of the lever arm on said bridging member interfitting with said insulating bushing, said bridging member adapted to exert equal pressure on each terminal when the switch is in closed circuit position.

6. In an electrical switch, an electrical conducting bridging member having ofiset blade arms, a rectangular-like opening -in the center of said bridging member, a pivot interfitting with said rectangular-like opening whereby said bridging member may oscillate or move in a linear direction, an integrally formed lever arm on said bridging member, the tip of said lever arm upturned, means to move said tip whereby the bridging member may be oscillated, and terminals arranged to be bridged by said bridging member.

'7. YA snap switch comprising an insulating base, a forked trigger pivotally mounted, a throw arm pivotally mounted, a spring connected between said trigger and said throw arm for pressing said throw arm in a direction towards the base and also iorimparting rapid movement from the throw arm when the trigger is moved to a predetermined point, a plurality of fixed electrical terminals, -a pintle on said base positioned between said terminals, an electrical bridging blade for engaging said terminals to close the circuit or to be disengaged from said terminals to open said circuit, an insulating bushing, said bushing interfitting with an elongated opening in the free end ofsaid throw arm, said bridging blade having an enlarged opening for receiving said pintle, a lever arm connected to said bridging blade, said lever arm being substantially parallel to said throw arm, and a portion of said lever arm interfitting with a recess in said bushing whereby movement of said throw arm will oscillate said bridging blade about said pintle.

- CLARENCE JOHN HATHORN. 

